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UNITED STATES PATENT OFFICE.

ARMAND MljLLER, OF NEW YORK, N. Y., ASSIGNOR OF TWO-THIRDS TO M. E. WVALDSTEIN AND A. H. MAAS, BOTH OF SAME PLACE.

PROCESS OF TANNING WITH SULPHOLEIC ACID.

%IPECIFJICATION forming part of Letters Patent No. 338,182, dated March 16, 1886.

Application filed May 15, 1885. Serial No. 165,551. (No specimens.)

The invention consists, broadly, in the application of the sulpho compounds of oils and fats, the sulpholeates, the alkali-sulpholeates, or sulpho-ricinoleates, commonly known in dyeing under the name of Turkey-red oils or alizarine-oils, in the art of tanning, in place of fats or oils, or emulsions of oils or fats, whether in bark-tanning, alum-tanning or tawing, oil tanning or chamoising, iron tanning, chrome-tanning,- or any other in which oil or its equivalent is used, and whether employed alone or as soluble sulpholeate salts in con- 2 5 junction with oxides or'hydroxides of the metals or of the alkaline earths-such as iron, copper, zinc, tin, mercury, chromium, cal- V cium, sodium, or potassium, or mixed with an anti-ferment soluble in the sulpholeatesueh as carbolic acid, salicylic acid, birch-oil, Ste.

The rationale of tanning finds, in general, perhaps its closest analogy in those processes which are applied to mordant vegetable fiberthat is, to place such fiber in a condition in which it is capable of receiving a dye and permitting it to become fixed.

In tanning animal skins almost precisely the same substances are produced as resultin mordanting vegetable fiber, and these substances, by deposit upon the membranous fibers, produce the desired effect. This is the action in the use, for example, of the various ordinary tanning substances; furthermore, of the hydroxides of iron, of aluminum, of chromium, but especially in the use of oily bodies or fats, as these are employed in Turkey-red dyeing, where the point is to impregnate the fibers or supply the interstices with triglycerides, (oils or fats,) or with free fatty acids, in such manner that the fiber will not suffer material change in its power of imbibition, and to which end it was customary to employ smooth emulsions consisting of oil and alkaline carbonates, until I substituted for such emulsions my so called water soluble Turkey red oils or alizarine-oils, (being solutions of unchanged or normal triglycerides in alkali sulpholeate or sulpho ricinoleate-that is, sulpholeic or sulpho-ricinoleic salts,) which products distinguish themselves by an extraordinary diffusibility, While they part with the unchanged or normal oil or the free fatty acid held in mere solution, partly by dialysis, partly by decomposition of the alkaline sulpholeates in drying, and deposit it. I have discovered that in the same manner, relatively, large quantities of oil or fatty acids may be fixed in membrane in a simple way with ex traordinary facility, and in a Very short time the membrane by contraction of its organointerstitial matter being placed in condition to exert powerful dialytic absorptions or de compositions, and by structural change capaeitated to unite with other bodies substances of a colloidal nature-such as tanning substances, aluminous hydrate, 850.

Up to the present time, so far asI am aware, the sulpholeates have not been employed in tanning, and I believe that they are destined to effect a great improvement in this industry. They present ready means of effecting the requisite and proper absorption 0foils,fats,

or fatty acids in the shortest possible time, in the most rational manner, and with a considerable saving of material. This refers as well to the manufacture of common tanned leather that is, to ordinary red or bark tanning-as to tawing and chamoising; and, furthermore, these great advantages are presented, that combinations may be effected that insure a firmer fixation of the other tan-stuffs, (tannin, alum,) whereby much tougher leather is pro duced. The benefit derived from the use of these oils is due to the fact that they are sol uble in water, contain large quantities of undecomposed or unchanged oil or free fats or fatty acids, and present these in a manner and condition to permeate the skins with great ease and uniformity, thereby also effecting great saving in material and labor.

The oils or sulpholeates are to be produced in the well-known way, (see German Patent 1,488, September 27, 1877, and Dinglers Polytechnic Journal, 1884, Volume 251, page 499, and Volume 254, page 302,) by the gradual action of twenty-five to fifty per cent. sulphuric acid upon triglycerides, oil-seeds, &c., as well as upon semi-liquid and fixed fats, with neutralization of the resultant acid sulpho'mixture by means of potassium or sodium hydrate or ammonia.

The gist of the invention may be stated as follows: In tanning leather of the various kinds and by the various processes the use of oil plays an important part, and the same has been applied in various ways, though principally as an emulsion, with alkalies or their carbonates, or as an emulsion containing a free fatty acid. Now, I have found that the whole tanning process may be greatly improved, shortened, and simplified by using sulpho compounds or mixtures of the sulpho compounds of the various fats and oils with fats or oils or free fatty acids-that is, by the use of the so-called Turkey-red oils.

I will give some examples of the application of the sulpholeates in the different methods of tanning, with the changes and the new procedure to be observed in each case.

I. Red or Bark Tanning with Sulpholeates. First proceeding: The well cleaned and properly-swelled hides are placed in a neutral, five to seven (more or less) per cent. sulpholeate solution. (Described farther on.) After the expiration of a few hours they are to be taken out, allowed to drip and to dry in the air or in a damp heated chamber, whereupon after complete drying they are washed, and the operation is repeated to completion. The remaining oil preparation can always be employed anew without particular addition thereto. The hide thus prepared and nearly tanned is now placed in the tan-vat in the usual manner, or may be subjected to-any other process, as to a process of quick tanning. The hide with an equal quantity of tan-stuff absorbed is tanned in half the time,is much better in quality, and never brittle. The leather is now treated as usual and fatted or oiled, though again, in place of fat or oil or degras,

- a six (greater or less) per cent. sulpholeate solution may be employed, and finally the hide is dried and washed. This washing, however, may be omitted.

Second proceeding: The raw hides are softened, cleaned, swelled, and tanned in the usual manner, and then, instead of being smeared or stuffed with fats, oils, or degras, they are passed through a seven to ten (more or less) per cent. solution of sulpholeate in lukewarm water, whereupon they are allowed to drip, and are then slowly dried. In place of pure sulpholeate solution, acid sulpholein, or acid sulpho-ricinol, (castor-oiL) iron oxide, which is produced by the solution of chloride of iron in concentrated alkaline sulpholeate, may be employed. The leather is then at once bark, iron, and oil tanned, and may be colored with logwood with much finer effect than ordinary leather.

II. Alum- Tanning or Tawing with Application of SuZph0Zeates.The hides tanned by the usual process of tawing have, as is well known, the. disadvantage that by water a part of the alum-clay or argillaceous earth is withdrawn from them, whereby their strength is much reduced. This evil can best be overcome by the application of the sulpholeates, either before or after the actual tanning with the alumina salt and of asolution of chloride of sodium. By this application insoluble aluminium-sulpholeate is formed, together with free triglycerides orfatty acids. The argillaceous earth is hereby firmly fixed, and the leather acquires, with increased solidity, coupled with flexibility and softness, a finer appearance. The sulpholeate solutions are admirably adapted to replace the yelk of egg in the manufacture of kid gloves. To the oil solution, according to the French method, some phenol (carbolic acid) is added, though any other suitable soluble substance having a similar effect-such as salicylic acid, tar-oil, 8tc.may be employed to counteract the too strong heating of the stuffed skins when laid or spread that is, stored to cure. It is apparent that the sulpholeates may also be employed in the Knapp iron as well as in the chrome process. Here, again, the advantages of increased solidity and toughness, together with softness, appear, because diffusion is rationally more complete than by the application of soap solutions. The Knapp iron soap may with advantage be replaced by the above-described aqueous ironsulpholeate solution.

III. Ohamoising or Oil-Tanning by the Sulphaleaies.-The skins, prepared as usual, are passed through a twenty-five per cent. (more or less) Turkey-red-oil solution, whereupon they are allowed to dry, are laid in a moderately-warmed room in a heap, and are carefully covered over. They are then hung up in the air and allowed to dry slowly, when they are again oiled in the same solution after they have been laid in lukewarm water to rid them of any adhering unchanged alkaline sulpholeate, are filled, again laid in a heap, again dried, and then treated with aweak solution of alkali. The expressed and dried leather is then stretched and rubbed to give it flexibility, which has been somewhat lost in drying, and it is then completely oil-tanned. The results may be variously modified by greater or less concentration of the Turkeyred-oil solution, by higher temperature in drying, as also by more frequent passes or dippings. In all cases the absorption of the fats and fatty acids takes place sooner, more evenly, and with greater certainty than in the ordinary procedure, and there is no loss of fat, inasmuch as the remainder of a solution may be applied with equal effect with one freshly prepared. Combinations with the salts of alumina may also be employed here.

The method preferred is as follows: Steep In the art of tanning, the improvement 10 the prepared skin in a solution containing, which consists in treating the skins with preferably, fifteen per cent. of the soluble oil, sulpholeates, substantially as described. dry, and, if necessary, repeat the operation, In testimony whereof I afiix my signature 5 and then proceed in the usual manner of tanin presence of two witnesses.

ning, according to the kind of leather desired. ARMAND MULLER.

Having thus described my invention, what Witnesses:

I claim, and desire to secure by Letters Pat- R. G. DYRENFORTH, cut, is J ULIUs GOLDMAN. 

